The _MOUSEWHEEL function returns a positive or negative INTEGER value indicating the mouse scroll wheel clicks since the last mouse read.
- scroll% = _MOUSEWHEEL
- Positive return value of 1 represents one "click" the mouse wheel was moved toward the user.
- Negative return value of -1 represents one "click" the mouse wheel was moved away from the user.
- After a "click" has been read, the value resets to 0 automatically.
- If no movement on the wheel has occurred since the last _MOUSEINPUT read, _MOUSEWHEEL returns 0.
- You may want to use a cumulative mouse wheel scroll value using a total variable.
Example 1: Reading the cumulative mouse wheel "clicks" (Enter quits).
Example 2: A simple text scrolling routine using the mouse wheel.
DIM Array$(100) LINE INPUT "Enter a file name with 100 or more lines of text: ", file$ OPEN file$ FOR INPUT AS #1 DO UNTIL EOF(1) inputcount = inputcount + 1 LINE INPUT #1, Array$(inputcount) IF inputcount = 100 THEN EXIT DO LOOP FOR n = 1 TO 21: PRINT Array$(n): NEXT CLOSE #1 DO DO WHILE _MOUSEINPUT row = row + _MOUSEWHEEL IF prevrow <> row THEN IF row > 0 AND row <= inputcount - 20 THEN CLS: LOCATE 2, 1 FOR n = row TO row + 20 PRINT Array$(n) NEXT END IF END IF prevrow = row LOOP LOOP UNTIL INKEY$ > ""